Red plant and lighting

[jacian]

[/quote]

Moderator,

Is it possible to put the info on PL lighting (provided by bclee in the above posting) in the Aquatic FAQs?
----------------
[/quote]

Done

[robin]

Another question,
Will the leaves that has turned green turn back to red under sufficient lighting? and right chemical compositions?

Regards
Robin

[Cardinal Tetra]

hi, i just bought a red plant (lotus?) at the LFS just now. i noticed that some leaves are already turning green. my tank is a 2ft with 1x18W FL + 2x18W FL
should that be ok? i was wondering if the plant would turn red again if given enough light. or do i have no cut off the green leaves?

[kadios]

Other than strong lighting, red plants need additional Iron on top of the usual and basic fertilizer in order to be red.

Cheers!

[naturetan]

No experience with red lotus plant, so can't comment.

My observation about red stem plants is that it would not be easy for green ones to turn red. But if conditions are right, new growth would be red. Well, you can wait for new growth to see how it goes.

I've seen tank running at very low light with CO2, about 1.5 gal/W, yet its Rotala Macrandra is rosy red! Plants like MM and riccia are growing very green. Not only that, the hairgrass and glosso are creeping everywhere.

This has become very interesting to me, and I'm still observing the tank ecology. Well, the trick might be placing the lighting directly under the red plants, as suggested in my earlier post. Using PL light, IMO is better for this purpose, since it's generally more intense and penetrative. Sometimes, the wattage of the lights might tell nothing, if it has poor intensity or wavelength for photosynthetic purpose.

However, I don't have a definite answer, and guess we need to experiment more to discover it ourself.

[Plantbrain]

Folks this issue was dicussed for a number of years on the APD.

Lighting plays less of a role than folks think/believe and what many books would have you believe.

What does play the significant role in most red coloir in plants is NO3 levels.

For example, maintain the same light, the same chemical composition.

Then using a good NO3 test measure the NO3 and note the effects of certain red plants.

Most red plants will turn redder at kless than 5ppm of NO3.

Adding a good size dose of KNO3 will green the plant.
Having a few fish/some fish waste will help achieve a lower threshold of NO3 levels since some Nitrogen will be from fish waste in the form of NH4.

But you all can do this yourselves with Rotala species, Ludwigia is also a good plant to work with.

Now if you let the NO3 get too low, then you will stunt your plants and that's far worse than a green plant.........
careful........

Regards,
Tom Barr

[robin]

I am trying to increase my tank to 3 wpg to see the result.

Cheers

[Plantbrain]

At high light do you believe it would easier or more difficult to maintain a low NO3 level supply and NH4 in the form of fish waste? And why......

Think about uptake rates.

2-3w/gal is plenty for any red plant I've ever had.

More is not better.

Regards,
Tom Barr

[robin]

I am getting pretty confused now, so is high light good for my red plants so that they remain red or should i go low light so that they will become red ?????

Any lao jiao can comment?

[kadios]

Hi plantbrain!

So can I confirm with you that in your case,

Lighting was moderate
CO2 and other fertilizers as per normal
Iron and traces as per normal
Low NO3 levels

Normal as in not purposely dosing more Iron or Macro or Micro nutrients in particular.

Btw, may I know your fertilization regime? Weekly, daily? I presume daily for better control of NO3 right? Top up when used up instead of creating a "reservoir of nutrients" for which the plants can tap from?

Thanks in advance!

Cheers!

[robin]

argh, i am still as confused

[PeterGwee]

As long as lights falls between 2-3W/G, it should redden plants up if K,P,traces, CO2 are kept in good range while allowing the NO3 to fall below 5ppm. Noted that most kits we use are not precise enough for the job and would end up stunting the plants instead if we push it too far. When plants are stunted, that is when algae comes in to attack. []

[bttay]

High light is definately necessary for red plant. I have just bought a red plant (yet to find out its name). Initially, only a few leaves were red. When I increased my lighting to 4w per gallon, most of the leaves that face directly to the light bulb turn red.

I think nutrient plays important role. But I have just over fertilized my tank and am having a big algae boom.

[sherchoo]

Robin,
Please read plantbrain's first posting carefully and try to understand.

[bttay]

I have a question on Iron supplement. My iron is tested to be between 0.1 to 0.2 ppm. I know that red plant needs more iron. Should I add further iron supplement?

I afraid that overdose of iron might cause manganate deficiency and algae boom.

[naturetan]

Robin,

Tom Barr has stated that having plants growing redder does not really depend on high light, as I've somehow suggested in this previous posting from observation. The relationship between maintaining lower NO3 (<5ppm) and getting redder plants play a more important role.

Inorder to maintain a low NO3 and yet not stunt the plants quickly, lower lighting will be easier to control - since it has slower intake of nutrients. Besides having some fish waste, maintaining NO3 around 1-4ppm will help solved your problem.

Hope this is clear. Try this out and see how it goes.

[Plantbrain]

Okay think about it like this.

More light = more uptake/faster growth.

Higher light often yields redder growth since now the uptake rate is higher nd this lowers the NO3 levels in your tank.

But wait a little while, now you have run out of NO3 and the tank starts to look shabby, lack luster growth, and finally some algae.

Seem familar?

It's like driving a car. The faster you go(speed= light intensity), the more gas you use(gas= nutrients).
If anything goes wrong at higher light, your "crash" will be worse and you'll have more algae problems.

Less light is safer if you miss dosing times or cannot seem to get enough CO2 to reach 25ppm etc.

So at 1w/L, you are going to need high CO2/enough NO3/PO4/Traces/ to last till the next dosing.

For this light level you need to dose about every 2-3 days and most of the % of Nitrogen assimilated will be NO3.

At 0.40w/L you can likely go a week without dosing and the % of nitrogen that is NH4 will be higher and less of the NO3.

NH4 comes from critter waste etc.

Adding more fish/critters to supply the plants with Nitrogen causes algae in moderate to high light tanks.

Non CO2 tank grow slow enough that the Nitrogen needs are met solely by fish/critters.

My non CO2 tank had the reddest plants also.

As far as red plants needing more iron, I doubt there's anything to this.

The red color, is namely from the anthrocyanin. This pigment is thought to be a namely signaling compound for critters/pollinators/UV protection.

There is _no_ iron whatsever in this compound.

It is thought to exist in plants as super molecule bound together in chains be copigments and metal ions, but these happen to be Mg, not Fe(iron).

Plants make many Flavinoids which this chemical belongs to and many other colored pigments(pink, purple, blue etc).

There are many different products a plant makes along this PAL pathway. The red coloration is one of the last along this "production line" of chemicals and iron's main role is that of enzyme co factors/electron transport.

All plants need these chemicals along this pathway to grow and function. Red doesn't seem to matter much here.

I think the more iron idea came out of red=ferric oxide, rust. Perhaps since more light = more/faster uptake, the idea was the plants needed more iron, which is true but not any more than the green plants, you just couldn't see them change color unlike the red plants.

Now whether you got any of that or not does not matter really. The main thing is to come away with something. You'll gop backj later, months/years etc and get more from it as you go along in this hobby.

You can try this yourselves and see.
Crank the CO2/add K/PO4/more traces than you think you need, and then add your normal routine of KNO3.

But this time wait a day or two longer and see if the plants redden up. Now add the KNO3, say 1/4teaspoon per 20 gallons, do the plants turn green again?

This works with most color variable species but not all.
Allowing the NO3 to drop down will change the color.
N limitation can produce less green color in many plants and this allows the red to be seen also.

Too much NO3 you get green plants, too little and you stunt your plants, it's a bit like a drug, there's a fine balance between effective results and killing the patient or not doing anything useful at all.

Regards,
Tom Barr

[Fei Miao]

It's interesting what Tom said; I had similar experience with my 80 L tank last year, my lights were only 36watts then but my ludwigia repens were really "red", at that time I thought the low temp. we were experiencing had a part in the reddness...

[robin]

Thanks a lot to plantbrain and everyone who has contributed, somehow I still cannot get my NO3 to drop below 5, seems to be always at 5

Using sera test kit.

Robin

[Plantbrain]

Robin, unless your feeding, adding KNO3, the NO3 should drop. The test kit is always suspicious.

You can see about the NO3 by using your tap water as the gauge. Call them and see how much NO3 is present(likely not much) then do large water changes and add KNO3. The estimated/theoretical NO3 level to that volume of water should be very close to what the test kit shows, if not, ignore the test kit.

Realistically few people test their NO3 daily for years and try to maintain a very close range on their NO3 levels. Too much work and impractical.

What folks do is guess their NO3 needs/uptake rates=>dose accordingly and add/balance the fish load to achieve a good range. Sometimes they over do it and the plants turn green. Sometimes they under do it and the plant stunt.

But you do a water change and add fresh nutrients back and start again.

It's easier than testing all the time.

Regards,
Tom Barr